Researchers helped provide a rare glimpse into how the great Chinese firewall really works

According to researchers from the University of New Mexico and University of California, Davis, the firewall used by the Chinese government to censor Internet material is not really as secure as the government wants users to believe. Researchers discovered that much objectionable content could still be viewed, especially if online traffic was high.

Instead of simply blocking all web sites that feature content on a banned subjects, the Chinese government chooses to use a large dragnet that looks for the use of banned words. If the Chinese system detects any banned words, reset commands are sent to the source and destination of the banned word. Researchers found that the "'resets' effectively break the connection" so results will not be returned.

This different type of filter ultimately encourages a certain level of self-censorship - since Chinese users know that selected words are taboo, the users may choose to avoid the topics altogether.

"Imagine you want to remove the history of the Wounded Knee massacre from the Library of Congress," said Jed Crandall, University of California, Davis assistant professor of computer science. "You could remove 'Bury My Heart at Wounded Knee' and a few other selected books, or you could remove every book in the entire library that contains the word 'massacre.'"

Both universities who took part in the study are now collaborating to work on ConceptDoppler, a tool that is able to give researchers a report if censorship in China changes.

Internet censorship in China runs rampant, with a number of popular web sites not available to traditional Internet users. The Flickr photo sharing web site successfully loads, but users are greeted with a screen without images. Several different popular online blogging services also cannot be used by Chinese users.

The Great Firewall of China web site allows users to test if a specific URL is blocked by the Chinese firewall.